+Project 1 Sustainable Electric Toothbrush Design Report
Rui Liu
Brian McKellar
Tom Dittman
Brendan Pinder
Date 9/28/2012
Team 8
Abstract
Project 1 was to analyze an electric toothbrush from Oral-B and decide on ways to
redesign the product to increase the sustainability. We were given an electric toothbrush to
dissect and look at the advantages and disadvantages of each of the single parts included in the
brush. The batteries are the main part to be analyzed because we are trying to make it more
sustainable and they are the main power source. We should also consider improvements in
materials to make the toothbrush more sustainable and environment-friendly. The task after
analyzing was to generate new concepts that could improve the electric toothbrush. The new
concepts we used to improve the toothbrush were a custom fit brush head, a micro motor
vibration mechanism, an all-round grip, BPA-free plastic, a curved body and a waterproof charge
station. The custom fit brush head reduces the amount of material used on replaceable brush
heads. The micro motor vibration mechanism reduces energy consumption. The BPA-free plastic
is more eco-friendly and the charge station reduces waste from batteries. Altogether these
features make the toothbrush more sustainable.
1.0 Introduction
Only 11 % of devices that were at the end of their battery life last year were recycled.
The project that we have been given is to redesign an electric toothbrush to make it more
sustainable therefore to relieve this problem of electric devices not being recycled and harming
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the environment. For this to be done new concepts need to be developed to increase the life span
of the electric toothbrush.
The price of an electric toothbrush averages approximately 20$ but can get as expensive
as 100$ for the newest models. The current cost does depend on how much consumers are
willing to pay and therefore consumer needs have to be taken into account when redesigning this
product. The brush that is being redesigned is the Oral-B AdvancePower 400 Bright which can
now be found very cheap because there are many newer models as it was first produced in 1978.
Thus far, we have analyzed the toothbrush and all of its parts by taking it apart in the
design lab. Measurements of the battery power and life were also taken. Another task we have
completed is surveying consumers on what their top priorities are when purchasing an electric
toothbrush. In the sections to come we will provide the results that have come from completing
these tasks and ideas we have come up with to make the toothbrush more sustainable.
1.1 Initial Problem Statement
The problem that needs to be solved in this project is discovering a way to make an
electric toothbrush last longer to eliminate items that harm the environment from not being
recycled. This will be done by deciding what the flaws were with the brush and finding a way to
fix the problems and make the brush last longer. Other than increasing the life span of the brush
we would like to design the brush in a way that makes it easier to recycle.
2.0 Customer Needs Assessment
We gathered our information on consumer needs by coming up with what we thought
would be the most important features of an electric toothbrush. Next we created a survey that
asked the consumer questions about these aspects of the brush to see what they considered most
important. We surveyed 12 people and we compiled the results for interpretation.
2.1 Weighting of Customer Needs
Next up we designed a list of customer needs, weighing which of the categories the
consumer considers to be most important when purchasing a new toothbrush. We used an
Analytic Hierarchy Process, or AHP, to weigh these needs numerically. Some of the less
important categories we eliminated if it seemed that no consumer is concerned with the category.
Weighing the customer needs was the key to designing a more popular electric toothbrush that
the public will actually want to purchase over other toothbrushes. Table 1 discusses the initial list
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of customer needs that we decided on from the results of the surveys. Table 2 is the subdivision
of the main customer needs. Table 3 is the detailed weighting of the categories and the main
objective which is sustainability.
Table 1. Initial Customer Needs List Obtained from Team Focus Group
Safe
Sustainable
Recyclable
Battery Life
Quality
Cost
Aesthetics
Size
Weight
Table 2. Hierarchical Customer Needs List Obtained from Focus Group
1. Safety
1.1 Water proof
1.2 Soft bristle
2. Quality
2.1 Low Noise
2.2 Long-lasting bristle
2.3 Easy to change brush head
2.4 Not easily broken plastic
3. Sustainability
3.1 Rechargeable batteries
3.2 Easily recyclable
3.3 Eco-friendly manufacture process
3.4 Relatively maintenance free
4. Cost
4.1 Low manufacturing cost
4.2 Cheap replacement
4.3 Retail cost under $30.00
5. Battery Life
5.1 Long battery life
5.2 High battery efficiency
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Safety
Sustainability
Battery Life
Quality Cost Total
Weight
Safety
1
4
7
3
5
20
.38
Sustainability
.25
1
4
.5
5
10.75
.20
Battery Life
.14
.25
1
.14
.2
1.73
.03
Quality
.33
2
7
1
3
13.33
.25
Cost
.2
.2
5
.33
1
6.73
.13
Figure 1. AHP Pairwise Comparison Chart to Determine Weighting for Main Objective
Categories
Rechargeable
Batteries
Easily
Recyclable
Eco-Friendly
Manufacturing
Relatively
Maintenance
Free
Total Weight
Rechargeable
Batteries
1
4
5
2
12
.46
Easily
Recyclable
.25
1
3
.25
4.5
.17
Eco-Friendly
Manufacturing
.2
.33
1
2
3.53
.14
Relatively
Maintenance
Free
.5
4
.5
1
6
.23
Figure 2. AHP Pairwise Comparison Chart to Determine Weighting for Sub-Objective
Categories
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Table 3. Weighted Hierarchical Customer Needs List
1. Safety(.38)
1.1 Water proof
1.2 Soft bristle
2. Quality(.25)
2.1 Low Noise
2.2 Long-lasting bristle
2.3 Easy to change brush head
2.4 Not easily broken plastic
3. Sustainability(.20)
3.1 Rechargeable batteries(.092)
3.2 Easily recyclable(.034)
3.3 Eco-friendly manufacture process(.028)
3.4 Relatively maintenance free(.046)
4. Cost(.13)
4.1 Low manufacturing cost
4.2 Cheap replacement
4.3 Retail cost under $30.00
5. Battery Life(.03)
5.1 Long battery life
5.2 High battery efficiency
3.0 Revised Problem Statement
After reviewing the results from the customer needs survey and completing two AHP
charts, we have been able to refine our goal to a much more specific objective. Our customers
have put two other categories above our original objective of sustainability. The consumer has
told us that safety and quality are more important when considering buying a new electric
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toothbrush. However, we cannot forget that the main goal of this project is to design a more
sustainable toothbrush. Consumers do not really care as much about the life of the toothbrush as
much as the quality or safety. This makes sense to the general consumer not concerned with the
aftermath of throwing their old toothbrush away.
We had a few general areas we decided to fix first with the original design of the
toothbrush. The batteries are a big waste of space and size in the design. A few ideas we have
decided upon are rechargeable power supply units instead of big AA batteries, whether that be
capacitors or smaller, rechargeable batteries. Battery waste would cut down on harmful waste to
the environment, therefore making the toothbrush more sustainable. The safety of the power
supply is necessary to be taken into account due to safety being rated higher by our customer
survey. Cost is another section our customers care about, not as much as sustainability, quality,
or safety, but we should still consider trying to lower the costs.
The materials of the toothbrush are another area we considered improving upon. The
plastics used consume a very large amount of energy to mold the casing. Also, the ability to be
recycled of the materials is another very important factor in the sustainability because after the
toothbrush is recycled we want it to do so naturally or at least better than before. We also need to
consider the safety and quality of the materials so it is at least as safe and durable as the previous
versions of the toothbrush. The life of the toothbrush must also be taken into consideration if we
want to cut down on the amount of waste created by discarded toothbrushes.
4.0 External Search
This section of the report we will focus on how our product will compare to those of the
past and from other countries, show some of the inner workings of the original model and
statistics of the areas we think we could improve upon in our new design and the legal resources
necessary to design and manufacture our product.
4.1 Lab 1 & Lab 2 Report
In Lab 1 we analyzed the product and inspected the different parts of the electric
toothbrush and how it was manufactured. We first completed a visual inspection of the
toothbrush deciding how many detachable parts it contained and how those parts functioned in
the toothbrush. For example, the brush head is made with soft bristles to comfort the gums and it
oscillates back and forth to clean the teeth. Also in Lab 1 we examined the use of the brush and
the simplicity of it such as the placement of the on/off switch on the handle for convenience.
Next we researched the cost of this electric toothbrush and others to see the range of retail price
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the average being approximately $19.99. This model was discontinued but there are many newer
models of Oral-B electric brushes still sold.
Lab 2 was the actual disassembling of the product and taking power and noise
measurements of the brush. We took a decibel reading of the noise of the electric brush from
different lengths away from the device and obtained an average noise level of 66.1 decibels.
Next we took a power measurement of each of the AA batteries and measured the current value
with no load and under 4 load conditions. The average current value with no load was .27 amps
and under load .585 amps which led to a calculation of the battery life being approximately 114
days before replacement. We labeled each part of the toothbrush inside and out and estimated the
time it took to dissect that part. Finally, we looked at the main parts: the brush head, the body,
and the bottom cap, and we discovered the sub-assembly and components of each main part and
created a bill of materials table of main parts of our product .
Table 4. Bill of Materials
4.2 Patent Search
Table 5. Art-Function Matrix for Electric Toothbrush
FUNCTION
ART
handle, attachment, motor
Main Body
Removable Brush Head
replaceable head
multi-motion toothbrush
rechargeable batteries
US 597415
US 6836917
Oscillating Head
US 7340794
US 6928685
Charging Station
US 6798169
During our patent search we looked into many different sections of other electric
toothbrush designs by using google patent search. We looked into four main sections that we felt
were important to include in the patent search; the main body, removable brush head, oscillating
head, and charging station.
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The main body of the typical electric toothbrush is necessary to hold the motor in the
smallest possible area, so the product does not become too large. The body also has to be strong
enough to hold the motor and inner-workings in the casing without breaking during normal use.
The next section of our patent search was the replaceable head for the toothbrush. This is
important to the consumer so they only have to purchase a new head instead of a whole new
toothbrush. The fact that the head comes off as well will also help the consumer clean the head
regularly, as the head will most likely become dirty after a length of time.
The motion of the toothbrush head also comes into play with the next patents we found.
The motion of the head is important to the actual cleaning ability of the toothbrush. We needed
to find a working design that would make our toothbrush desirable to the consumer.
The last section of our patent search was the charging station. We thought this was the
most important patent to find because this was one of the big issues we had with the current
version of the toothbrush. Making the toothbrush rechargeable will in turn make it more
sustainable while simultaneously cutting down the amount of waste from throwing away
batteries. Since our main goal is to make a more sustainable toothbrush, so this part of the
toothbrush seemed like the most important patent to find.
4.3 Product Archaeology
Throughout extensive research of the electric toothbrush we found many things. The
toothbrush was first used in 1498 C.E. in China and was made of hog bristles in ox bone. In
approximately the 19th century the toothbrush was reinvented and regularly mad, however hog
bristles were quite expensive so the toothbrush didn’t become a household item until the 20th
century in the United States. A family toothbrush became popular and widespread even among
families with low income. Part of this reason is due to the fact that nylon filaments replaced the
hog bristles. In addition wood and plastic began to be used in the handle over bone. The price of
toothbrushes dropped dramatically. The oral hygiene increased substantially in not only the U.S.
but also other industrial countries.
Manual tooth brushing is still the main method for brushing. Scientists agree that when
manually brushing correctly and for enough time that the manual toothbrush is acceptable. In
1855 Frederick Wilhelm, a Swedish clock maker, created the first mechanical teeth brushing
machine. It wasn’t until the 1960’s that electric toothbrushes started being regularly
manufactured and available to the public. By 1970 the manufacturing of electric tooth brush had
nearly ceased due to the suspect that they really weren’t better than manual toothbrushes. Since
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the however electric toothbrushes studies have revealed that they are very effective compared to
manual styles.
Information from The Role of Electric Toothbrushes: Advantages and Limitations by G.A. van
der Weijden, M.F. Timmerman, M.M. Danser, and U. van der Velden
Electric Toothbrush
Time (minutes)
Plaque Removed
1
75%
2
84%
6
93%
Manual Toothbrush
Time
Plaque Removed
2
42%
6
75%
Figure 3. Tooth Brush Archeology
Figure 3 shows the staggering superiority of the electric toothbrushes effectiveness
compared to the manual toothbrush. Information from The Role of Electric Toothbrushes:
Advantages and Limitations by G.A. van der Weijden, M.F. Timmerman, M.M. Danser, and U.
van der Velden
Most electric toothbrushes had a head that mimicked the manual electric toothbrush style.
We were given an Oral-B toothbrush to improve which has an oscillating and rotating head. This
rotating head has been found significantly more effective.
4.4. Benchmarking
In the table below, we compared our current toothbrush model to other three models from
two brands using a scale of 1 to 5 in order to get a deeper understanding of our toothbrush and
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current popular models in the market. We can also consider the advantages in different models as
references to our future improvements.
Feature
Oral-B Advance
Power 400 Bright
Oral-B
Power
Count
Price
5-cheapeast
1-most expensive
$19.95
Rechargeable
5-rechargeable
2-nonrechargeable
Anti-Microbial
Toothbrush 1
Oral-B Vitality Dual Clean
Electric Toothbrush
Spinbrush Pro Recharge Battery
Powered Toothbrush
$6.99
$32.99
$17.75
2
5
1
3
2AA Batteries
1AA Batteries
Recharge Base
Recharge Base
2
2
5
5
4
5
2
1
Simple but good
Ordinary toothbrush
design
Charming design with
elegance
Thick body makes it look clumsy
Packaging
5-uses less plastic
1-uses most plastic
Aesthetics
5-best looking
10
1-worse looking
3
1
5
2
Table 6. Benchmarking of Four Products
4.5 Design Target
Following the external search we have learned many new ways to improve our product.
Those ideas will be more clearly specified in the coming sections. The two labs, patent search,
product archeology, and benchmarking have let us see how our ideas compare with the current
model, models of the past, and other brands. We have also learned about the advancements over
the years in all kinds of toothbrushes, not just electric.
The target of our design project is to make a more sustainable toothbrush for the public.
A sustainable toothbrush is durable and lasts long without replacement. This eliminates waste
from people throwing away their old toothbrushes. Some manual toothbrushes are recyclable but
most people do not recycle them. The electric toothbrush takes more plastic to make, however it
lasts much longer. When the toothbrush head is old, all you have to do is buy a replacement
head. This is not only environmentally friendly but also cost friendly. From benchmarking the
product we learned that we should make the toothbrush with a rechargeable base while also
being aesthetically pleasing. The patent search also helped us come to a conclusion on what parts
we should use.
5.0 Concept Generation
5.1 Concept Generation
Human factor
body design
Power generation
and accessories
Energy mechanism
for brush head
Brush head design
Thinner Body
Rechargeable station
Motor vibration
Two-piece dual
motion
Curved Design
Rechargeable AA
batteries
Motor up & down
motion
One-piece dual
motion
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All-around Grip
Capacitor powered
Eccentric wheel
rotation
Rectangular brush
head
BPA-Free Plastic
Solar powered
Gear rotation
Dome brush head
Sliding Battery
Cover
Automatic turn-off
Motor rotation
Custom fit
Figure 4. Morphological chart
Human factor body design
● Thinner body - use less material and easier to hold
● Curved design - more ergonomic handle and ease of access to back teeth
● All-around grip - left and right handed
● BPA-free plastic - more eco-friendly and more sustainable
● Sliding battery cover - less material and easier to access batteries
Power generation and accessories
● Rechargeable station - no disposable batteries=less waste
● Rechargeable AA batteries - less waste from throwing away old batteries
● Capacitor powered - use less power, therefore making it last longer
● Solar powered - renewable resource, not harmful to environment
● Automatic turn-off - no extra use of power when not in use
Energy mechanism for brush head
● Motor vibration - motor vibrates to power brush head conserving energy
● Motor up & down motion - motor moves up and down the brush body
● Eccentric wheel rotation - wheels slide in different directions as a motor
● Gear rotation - gears rotate inside as a power mechanism
● Motor rotation - motor rotates normally
Brush head design
● Two-piece dual motion - different pieces move independently to clean deeper
● One-piece dual motion - moves in two directions to reduce user movement
● Rectangular brush head - more surface area
● Dome brush head - vibrates to clean teeth easier
● Custom fit - fits teeth all the way around and is able to clean all sides of teeth at once
See Appendix A for sketches
5.2 Concept Selection
We created four Pugh Charts to decide which concepts we would select from each category. For
the first category which was Human Factors Body Design we chose the all around grip and BPA
free plastic, with the BPA free plastic making it more sustainable and geared towards the
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consumer. Next was Power Generation and Accessories and we chose the rechargeable station to
reduce waste from batteries and also making the brush more practical. The Energy Mechanism
for the Brush Head that we chose was the motor vibration to conserve energy. We also chose a
custom fit brush head designed to individually clean every tooth and provide a satisfying
experience for the customer. See Appendix A for the Pugh Charts.
6.0 Final Design
The final design features a custom fit brush head with replaceable bristles, a BPA-free all-round
grip curved body, a micro motor vibration mechanism and a waterproof charge station. These
features match the primary objective which is sustainability and the main consumer needs which
are safety and quality.
1. Two-side custom fit brush head and micro vibration technology provide overall clean;
replaceable bristles save more materials than replaceable head.
2. All-around grip and BPA-Free Plastic provide safety to product users.
3. Curved body fits hand comfortably, providing pleasing experience.
4. Waterproof charge station cap provides safety.
6.1 Design Drawings, Parts List and Bill of Materials
These summarize and communicate your design.
Drawings should have scale information and must include:
1
2
3
A pictorial drawing (isometric) of your design
Principle views of the assembly and major parts. A Parts List is necessary if parts are numbered
in order to associate names with numbers.
Other details as necessary. Use professional conventions. Include all dimensions.
Do not draw details of standard hardware like nuts, bolts, washers, castors, computers, etc.;
just specify them in the Bill of Materials.
6.2 How does it work?
Our design is powered by a motor vibration that moves the brush head to conserve the amount of
energy each time it is used. The brush also has an all around grip that works for either right or
left handed people and is made with BPA free plastic that is safe for the user. Connecting to the
bottom of the brush is a charging station where it can be connected to a battery to be recharged.
7.0 Conclusions
Add a few concluding thoughts that summarizes your project. To what extent was your project
successful? To what extent does it meet the customer needs? What are the truly unique features
you have added to your design?
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References
Engineering Design: A Practical Guide by Madara Ogot and Gul Okudan-Kremer
The Role of Electric Toothbrushes: Advantages and Limitations by G.A. van der Weijden,
M.F. Timmerman, M.M. Danser, and U. van der Velden
Appendix A
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